Embryo transfer and multiple gestation

climate of political confrontation, and given the diverse historic How should the number of embryos background of settlements during the colonization of North transferred to the uterus following inAmerica (Quinn, 1995), it is not surprising that individual vitro fertilization be determined to liberties and the protection of the rights of local communities avoid the risk of multiple gestation? from abusive forms of government were pre-eminent concerns during the founding of the US. The Federalist Papers and Richard Bronson the debates occurring during the Constitutional Conventions eloquently bear witness to these concerns (Bailyn, 1993) Department of Obstetrics and Gynecology, Health Science which, ultimately, led to the development of a multilayered Center, S.U.N.Y., Stony Brook, New York 11794–8091, USA system of government, in which national, state and local Laboratory assisted reproduction, while aiding couples in the governments each play significant roles. Until recently, there establishment of pregnancies, has been associated with an has been no significant government regulation of assisted increased risk of multiple embryo implantation, resulting from reproduction, which has been left to the professional organizathe transfer of more than one embryo to the uterus following tions. However, driven by the recent exposure of possible in-vitro fertilization (IVF) (Jones, 1995). Women carrying two abuses discovered in some fertility centres, laboratory assisted or more fetuses are at greater risk of premature labour reproduction has fallen under increasing scrutiny. and pre-eclampsia, abruption, and their prematurely delivered This small group of articles will explore the specific issues infants experience greater shortand long-term morbidity that relate to the transfer of multiple embryos following IVF. (Melgar et al., 1991). The increased costs associated with the Why, in the first place, must several embryos be transferred care of these high order pregnancies, both in terms of the to the uterus following IVF, to achieve clinically acceptable treatment of premature labour and possible need for long-term pregnancy rates? Strategies to reduce this number would maternal hospitalization and the subsequent neonatal intensive diminish the intermittent risk of multiple implantation. Van care of their infants is also of concern. Yet how couples who Blerkom (1997) focuses on epi-genetic causes of the loss of have sought help in overcoming their inability to conceive, oocyte competence and new approaches that may improve their doctors, society and their representatives should deal with embryo implantation rates in the near future. Bavister and these risks remains controversial. While individuals can seek Boatman (1997) review the competence of current culture multi-fetal pregnancy reduction, this procedure is not without media to support the extended in-vitro culture of human its risks. The pregnancy loss rate reported in a recent large embryos and the possible transfer of fewer, more developed collaborative study varied from 7.7–22.9%, depending on the preimplantation embryos as a means of limiting the risk of starting number of embryos. The delivery of severely premature multiple implantation. Faber (1997) reviews the current social fetuses (,24 weeks gestation) varied from 9.0–22.9% (Evans forces within the US that have predisposed to the transfer of et al., 1996). large numbers of embryos. Bustillo (1997) explores the possible In some countries, embryo transfer has been regulated use of age-specific guidelines for embryo transfer to minimize through legislation at the national level. In the UK, a regulatory the risk of multiple implantations without deterioration in body has been created through an act of Parliament to oversee clinical pregnancy rates, and Palmer (1997) reviews the conIVF clinics. Only three preimplantation embryos may be flicting obligations of individuals and society in reproductive transferred to the uterus following IVF, irrespective of the health care. woman’s age, the couple’s religious background, or their First, I would like to return to the basic question of why it decision as regards proceeding with selective termination of is necessary to replace more than one embryo within the uterus pregnancy, should a multiple pregnancy occur (Lieberman to achieve clinically reasonable pregnancy rates. Embryo et al., 1994). Even more stringent rules have been promulgated quality and the receptivity of the endometrium are clearly through statutes in Germany, where it is not permissible to factors in the equation. If both variables are maximized, fewer fertilize more than three eggs recovered after follicular aspiraembryos need be transferred, limiting the risk of multiple tion (Beier and Beckman, 1991). This approach eliminates the implantation. Until recently, basic knowledge of the mechanism ethical dilemmas associated with both embryo cryopreservation of implantation was lacking, and while this area of investigation and multiple gestation. Unfortunately, it also lowers the overall is recently undergoing a renaissance, it is unlikely to yield chances of success for certain couples in achieving pregnancy information useful in the clinical arena for several years. A in any individual cycle and promotes the use of recurrent cycles considerable body of evidence, however, has accumulated that of hormonal stimulus and follicular aspiration, procedures not human reproduction is inefficient. Early embryonic loses during without risk. implantation also appear to be common, as evidenced by transient detection of chorionic gonadotrophin elevations in The American system of government evolved during a